The present invention generally relates to apparatus useable in conjunction with a subterranean well and, in representatively illustrated embodiments thereof, more particularly provides portable apparatus for extracting fluids, such as oil, gas and water, from a subterranean well.
Disclosed in Applicant's U.S. Pat. No. 7,007,751, the full disclosure of which is hereby incorporated herein by reference, is an apparatus for extracting oil or other fluids from a well. The apparatus is utilizes a fluid retrieval canister which is lowered on a cable into a well to receive well fluid therefrom. Once it receives fluid from the well, the canister is raised by the cable into sealed telescoping engagement with a vertically movable discharge head portion of the overall apparatus and compressed air is forced into the raised canister, via the discharge head, to discharge the received fluid therefrom for transfer to a storage container. The canister is then lowered into the well and the retrieval process is repeated.
While this well fluid extraction apparatus is generally well suited for its intended purpose, in testing of the apparatus it has been discovered that it is in need of improvement in three areas. First, over time the seal structure which sealingly engages the raised canister with the discharge head can become coated with operational contaminants and thereafter tend to cause the canister to hang up in the discharge head and undesirably resist release therefrom for re-lowering of the canister into the well. Second, when the gas pressure in the well is above a certain magnitude (representatively, about 10 psig) such pressure exerts an undesirably high upward force on the upwardly movable discharge head. Third, the apparatus is less than totally satisfactory in wells having vertically tilted upper casing portions to which the apparatus is connected because the connected apparatus is also in a vertically tilted orientation and thus subjects the cable to accelerated wear and stress.
As can be seen from the foregoing, it would be desirable to provide an improved well fluid extraction apparatus, of the general type described, in which these three operational problems are eliminated or at least substantially reduced. It is to this goal that the present invention is primarily directed.